Multiple smoke-signal unit



B. E. DEL MAR 2,945,222

5 Sheets-Sheet 2 N Q M n QM M m M Q am 0 m Sq 0 V n mm a l ww w 5 .Q m% B MULTIPLE SMOKE-SIGNAL UNIT July 12, 1960 Filed Dec. 5, 1955 July 12, 1960 B. E. DEL MAR MULTIPLE SMOKE-SIGNAL UNIT 5 Sheets-Sheet 3 Filed Dec. 5, 1955 y 1960 B. E. DEL MAR 2,945,222

MULTIPLE SMOKE-SIGNAL UNIT Filed Dec. 5, 1955 s Sheets-Sheet 4 BRUCE DEL MAR,

INVENTOR.

ATTORNEY y 1950 B. E. DEL MAR 2,945,222

MULTIPLE SMOKE-SIGNAL UNIT Filed Dec. 5, 1955 5 Sheets-Sheet 5 'loa 7?": Neal 95 95 4 02 I I I I I I I I BRUCE DEL MAR,

mmvron.

WZZ\%7% ATTORNEK 2,945,222 l Patented July 1 1950 MULTIPLE SMGKEESIGNAL UNIT "Bruce, E.v Del-Mar,1Los Angeles, (Ialifi, assignor to Del Mar Engineering Laboratories, Inc, ,Los Angeles, Caliii, a-corporatin Filed Dec. 5, 1955, Ser. No. 550,995

Claims. (11. 340-366) This invention:relates-to a 'device forzuse on an airborne vehicle to produce smokesignals to assist in visual orientation, identification andtrackingof'the airborne vehicle. The invention is particularly directed to an apparatus for this purpose that is capable ofcreating a plurality of such signals in controlled sequence.

Thepreferred method of producing asmokesignalis disclosedin the copending-Del Mar .application,'Ser. No.

410,392, entitledSmoke Signal Device, now PatentiNo. 2,923,930, which disclosure is hereby incorporated in the present disclosure by reference. The smoke signal is ,created by using a disposablecartridge that has at least one inwardly movable wall-to permit the cartridgeto the collapsed and discharged by exteriorly appliedfluid pressure. The cartridgeis placed in a chamber having :atmosphere. In somepractices of the'invention,:the.car-

. tridge contains inert 7 powder which may be tcolored ;to 3 produce -a colored smoke signal.

The;present invention is directed to "a -multipie-signal unit of this character which may the permanently'incorporated in the construction of an airborne -vehicle -.;or may be .in tthe form of a self-contained:stream-linedxhnit provided with shackleloops or shackle-lugs -to;p,ermit the unit to be temporarily mounted on theai'rborneevehiclaim the samemanner as a bomb or a jettisonablezfuel tank. 1

Thetpresent.apparatusmakes it possible to initiate an automaticsignal :cycle in which the individual smoke signals .are produced .at predetermined equal time intervals. 'Thus the smoke signals may be produced inimmediate succession in-a cycle to produce a composite continuous signal of relatively long duration or'may be ,spaced in time to create a dash-type-visual signalof longer overall duration. The present apparatus also .makes it possible, if desired, to. produce single smoke .2 relay, a normally closed relay .-for controllingzthev stepping relay and an intervalometer forwsending current pulses to the-normally closed relay.

The selector switch of the. master control.- mayzbe-rset for two difier'ent modes of operation. When theselector switch is set at its firstposition for what may? be termed the first mode of operation, aclosing .theimastersswitch results in automatic cyclicloperation of-the stepping-relay by the intervalometer inTcooperation-withthe normally closed relay. When the selector switch is-set: atits: second position for what may be termed the secondzmodenof operation, the, master control switch -is connected". directly to the stepping relay -to.create the individualxsmelrersig nals on demand, the master-control-zswitch-.beingrclosed and opened to prdduce-eachsignzil.

One feature ofithe invention isthatztwmsuchzselfecontained multiple-signal :units: may .be mounte'dij onxtan'aair- .craft to, provide twice as many'signals and ithe two 'con- ,trols may be connected-either in seriestonin parallelifor ruption, .the second multiple-signal unit wcontinues the ,cycle.

With the same-ser-ies arrangement, the selecterrswitch of the-first unit-may be-set .atits:first;.position andthe .selector switch of thesecond-tunit set ateits SGCOIIdr PBSition sothat when the master switch-is closed ttherfirst :unit will go throughits automatic a-cycle. thereafter---.the

second unit will=create individual .smokeasignalsinresponse to operation of the master control'gswitch; Also with the same :series arrangement, bothseleetor amits may be set at their-second positionstor-demand-operation by the masterv controlswitch, the first multiple-signal unit automatically. connectingtthe second multiple-signal unit with the-master--control switch when .-allof the :signal chargesrofthe first unit are exhausted.

The features .and advantages of vthe invention -.ma=y be understood from thefollowing.detaileddescriptien considered with theaccompanyingdrawings.

.In thedrawings, which are to beregarded:-as.1merely illustrative:

Figure 1 .is a side elevation of .the presently 5 preferred embodiment of the invention as a multiple-signalmnit adapted .to .be mounteddetachably on an :aircraft;

Figure. 2 is an enlarged side elevation-of. the .noserend of the, unit with housing .wall brokenaway;

"eontainedmultiple-signal unit includes a rotary stepping Figure3 .is a similar view oftheintennediate portion of the unit; a

Figure'4. is a similar view of thetail end of-themultiplesignalunit;

Figure 5 is a transversesection taken ralongtthedine 5-5 ofEigure 3'showinghowsix signal gunsraretstored .in the unit;

Figure 6 is an enlarged longitudinalrsectional viewof one of thesignal guns;

Figure 6a is an enlargeddetail of -Figu1-=e.6;

Figure 6b is alongitudinal sectional .view-ofavalveactuating. solenoid; t

Figure 7is an enlarged -cross sectionbf; the signalsgun valve taken along theline 77.of Figure..6;

Figure 8 is a-wiringdiagram of .the -control systemiof the multiple-signal unit;

Figure 9 is a diagram showing .how .two of:the-.signal units may beconnectedin. series "with the .mastencontrol switch for an automatic .signal cycle;

Figure 1O is,.asimilardiagram showing 'how twomultipie-signal units maybe connected in series with the masindividual smoke signals composite signal may be produced by the multiple-signal p unit when adjusted for a signal cycle with short time intervals between the individual signals;

Figure 13 is a similar view showing a dash-type composite signal comprising a succession of smoke signals at greater spacing that may be produced by adjusting the multiple-signal unit for cyclic operation at longer time intervals;

Figure 14 is a view partly in side elevation and partly in section showing a second form of collapsible cartridge for smoke-producing material, which cartridge has an end wall that functions in the manner of a piston in response to applied external fluid pressure; and

Figure 15 is a longitudinal sectional view of another form of collapsible cartridge containing powdered material to create a smoke signal, the cartridge having two frangible end walls.

General arrangement The presently preferred embodiment of the invention shown in the drawings is a multiple-signal smoke unit having a stream-lined housing made in separable sections, the housing including a central cylindrical section 20, a removable nose cone 22, and a removable tail cone 24. Preferably the central housing section 20 is provided with spaced shackle elements 21 whereby the multiple-signal unit may be removably mounted on an aircraft 23. As best shown in Figure 5, the central cylindrical housing section 20 has a rigid internal structure comprising an axial cylinder 25 and six longitudinal radially disposed partitions 26 that divide the interior into six longitudinal compartments 28.

The six longitudinal compartments 28 store six corresponding signal guns, each of which is generally designated by the letter G. As best shown in Figure 6, each of the signal guns G is of cylindrical construction and may comprise a forward pressure chamber 30 or highpressure fluid reservoir and an aft cartridge chamber 32 which normally houses a disposable or throw-away collapsible smoke signal cartridge 34. The cartridge chamber 32 is removably mounted on the end of the pressure chamber 30 by screws 31 and anchor nuts 33 so that removal of the cartridge chamber afiords access to the interior thereof to permit replacement of the cartridges therein.

The cartridge chamber 32 of each of the signal guns G has a discharge nozzle 35 (Figure 6) with a nozzle aperture 36 therein and since this nozzle aperture restricts the discharge flow, the size of the aperture determines the duration of a smoke signal. The cartridge chamber nozzle 35 has an interior screw thread as shown to receive the external screw thread 37 of a cartridge nozzle 38 and these two screw threads may be tightened by rotation of the cartridge to draw the forward conical wall 40 of the cartridge against the forward conical wall 42 of the cartridge chamber.

The cartridge nozzle 38 is closed and sealed by a thin frangible wall 44 that is designed to rupture in response to pressure internally of the cartridge. The cartridge 30 has .at least one inwardly movable wallso that the cartridge will collapse in response to external fluid pressure. In this instance, the whole cartridge is made of a soft metal alloy so that both the forward end wall 45 and the longitudinal cylindrical wall of the cartridge will readily collapse in response to fluid pressure thereby to cause rupture of, the frangible wall 44 with conseqnent discharge of the smoke producing content 46 through the nozzle aperture 36. As heretofore stated,

this smoke producing material may be, for example, titanium tetrachloride.

The pressure chamber high-pressure fluid reservoir 30 may confine compressed air at 650 p.s.i., for example, and has a normally closed discharge valve, generally designated 50 (Figure 3), for communication with the interior of the cartridge chamber 35. This valve may be opened when desired by means of an axial push rod 52 (Figure 6) in an axial tube 54, the push rod being in turn actuated by a suitable solenoid 55 (Figure 3) on the forward end of a smoke signal gun, the solenoid having an armature-57 as shown in Figure 6b.

The tail cone 24 is mounted on the central cylindrical section 20 of the housing in a suitable removable manner, the joint being a telescoping joint indicated at 56 in Figure 3. The tail cone 24 has six tail pipes 58 which are removably and telescopically connected with the corresponding cartridge chamber nozzles 35, as shown in Figures 4 and 6. Removal of the tail cone exposes the aft ends of the longitudinal compartments 28 for removal of the signal guns G therefrom.

The individual signal guns G are removably mounted in the individual longitudinal compartments 28. For this purpose, each of the solenoids 55 has an electrical plug 60 on its forward end that plugs into a corresponding fixed adapter 62. Each of the adapters 62 has an insulated Wire 64 connected thereto for energization of the corresponding solenoid 55, the solenoid being grounded to complete the circuit.

The nose cone 22 which is removably mounted on the central cylindrical section 20 of the housing along a telescoping joint 65 (Figure 2) forms a control compartment 66 for the control system of the multiple-signal unit. For the purpose of mounting the components of the control system, a circular frame member 68 is rigidly mounted on the forward end of the previously mentioned axial cylinder 25 and a longitudinal platform 70 extends rigidly forward from the circular frame member. The circular frame member carries the six fixed adapters 62 corresponding to the six smoke signal guns G, and the longitudinal platfom 70 carries a two-position selector switch 72, a rotary stepping relay 74, a normally closed relay 75 for actuating the stepping relay, and, finally, a suitable intervalometer 76 for controlling the normally closed relay 75.

Electrical control system The electrical control system of the multiple-signal unit is shown in Figure 8 in which the dotted rectangle 77 represents a multiple-signal unit. The rotary stepping relay 74 which is of a familiar construction that need not be described in detail, has a ratchet-actuated switch arm 78 that traverses a first series of six contacts 80 and a second series of similar contacts 82. The first series of contacts 80 are connected respectively to the previously mentioned insulated wires 64 that lead to the corresponding adapters 62 for energizing the smoke gun solenoids 55. The second series of contacts 82 are interconnected as shown and are connected to a wire 84, the purpose of the wire 84 being to permit two of the multiple-signal units to be connected in series.

The rotary stepping relay 74 includes the usual mechanical actuator 85 which is actuated by a grounded coil 86, the actuator and coil functioning as a solenoid. The mechanical actuator 85 carries a pawl (not shown) which is provided with a suitable spring (not shown) and which engages successive ratchet teeth (not shown) to advance the rotary switch arm 78. When the coil 86 is energized, it retracts the pawl in opposition to the pawl spring to engage a new ratchet tooth and does so without affecting the rotary switch arm 78. When the coil 86 is subsequently energized, however, the spring acting on the pawl causes the rotary switch arm 78 to advance one step.

The intervalometer 76 which is of a well known type "that need not be described in detail, includes a timing motor--88 and a normally open switch 90 that is controlled by the motor. The normally closed relay 75 comprises a relay arm 92 that is actuated by a coil 94. The" selector switch 72'has two switch arms 95 and'96 that are mechanically interconnected to operate in unison. 'Switch arm 95 is connected to an input lead 98 which is connected to a suitable voltage source through a master control switch 100 (Figure 9). As heretofore stated, if the multiple-signal unit is carried by a manned aircraft, the master control, switchltltl may be onthe'control panel in the aircraft, but if the airborne vehicle is not 'manned,,the master control switchlllt) may be operated by radio from a remote station.

At the. first position of the selector switch '72 which is shown in Figure 8 and which is used for the first mode of operation of the'unit,ithe"switch arm'95of theselector switch connects the inputlead 98 .with a wire 102 thatleads ;to one side of the :normally. closed relay 75. 'A Wire 104 branches 'from thewire 192;to one side of the intervalometer switch 90 and to onesi'de of. the intervalometermotorfis, the second side .of the motor: be- .ing grounded as shown. The other side. of the relay arm 92 is connected by a wire 105 'with the second arm t a contactll-tifiof 'the-selector,tswitch '72. A branch.

wire,f1"l0 connects the wire 106 with the rotaryswitch .arm 78. :Modes'of operation The manner in which the control system of Figure *8 serves llISfpllIPQSe may be 'understood'fromt-he diagram and the foregoing description. At-the start of a flight, the selector .-switch 72 is at its firstpositioinshown in Figure '8, 'the'master control switch 100 is open, the intervalometer-s-witch 90 is open, the relay '75-'is-in; its nor- -mal=closed -posi'tion,-thestepping relay coil 86is deenergized'and the rotary switch-arm 78 is at'its first-circuitclosing station. 'When the master control switch 106 is closed, it completes the following circuit'to 'energizethe stepping relay coil 86: "wire 98, switcharm 95 of the selector switch, wire 1G2, relay arm 92', 'wire 105;selector :switch'arm 96, and-wire 1-06 to one-side of the stepp'ingrelay coil 86, the other side-of the "coil being grounded. This 'energizationof the coil 86.. retracts the mechanical actuator .85 and .the pawl thereonagainst spring'pressure without shifting the rotary switch arm 73.

"With the switch arm '78 remaining at its first station, it,connects wirelli) with the insulated wire 64 at the firstLstepping relay .station toenergize the solenoid Q55 .of ithe corresponding signal .gun- G for creation of a smokesignal-in themanner. heretofore described. .After a predetermined time interval, the intervalometer' switch .910, is Q closed by ,the intervalometer..motor .88. for a brief I period. to open the normally closed relay.75 momentarily. =The..momentar.y:opening of the .relay .75.:permits. spring vactuation-of the mechanical actuator .85 .toiadvance the :rotaryswitch arm 78 to itssecond station. This advance- ,rnent ofthesrotaryswitch arm 7.8.immediately.closes .the circuit. through the solenoid .55 ..of the-next successivesig- .nal gunG. Thus closing 0f.the.master..contr0l switch 100 while tthe. selector switch ;72..is :at.its first-position causesithe sixlsignal guns G10 .helactuatedin sequence ..at equally spaced timeintervals.

If the time intervals :are substantially. equal .to 'the time duration of the individual smoke signals theresult .is a composite continuous signal such as shown in Figure 1'1 in which the individual 'smokesignals "112 are positione'd 'end'to end. 'Ifthetime intervals from initiation itojiliitiatidhdf'thesuccessive signalsare somewhat longer, the individual smoke signals 112 are spaced 'apart by Telatively short distances to produce the' longer-"compo'site dash-type signal shown inFigure 12. Still" longer time intervals between the starting points of the successive signals produces the elongated dash-type composite signals shownin Figure 13. Thus the composite signal-may be stretched out both in timeand in space and usually without loss of visibility.

Figure 9 showshow two signals -units may be connected in series with the'signal unit 77a "serving ;as a master unit andthe signal unit77bservingas a slave unit. It will be.noted that the selector switches 72"of both units areintheir first positions and'that 'the'pre- .viously mentioned wire, 84 from the master unit isconnected tothe'switcharm of .the slave unit.

When .the master .control switchltit) is closed, the master unit 77a operates in the manner above described to produce its'six signalsin a cycle and then .the rotary switch arm78 reaches thefirst of the second series of contacts 82 to .energizethe control circuit of the slave .unit 77b. 'As .the'rotary Switch arm "78 in the. master unit 77a traverses the second series of contacts".82, the intervalometer of theslavennit 77b .carries on the ,signal cycle without interrupt-ion by operating .thesignal ,guns of .the. slave .un-it in .the same-sequential manner.

0 Thusihetwo units cooperate-toproduce. a composite signal comprising .twelve. individual. smoke signals.

It is apparent from an inspection-cf Figure 8 thatsif .theselectcr switch 72 .is in its alternate second position .theseleetorswitch armBS will cooperate 'with the. switch 7 -contact q108 ..toconriect the master :controlaswitch .100 directly v withethecoil .-.86. .0f vthe stepping. relay 78. The six signahgunsGof the unit may. now be ,operatedone at atime .by closing "and opening (the master control switch 100. Closing the mastercontrohswiteh energizes ..the stepping. relay .coil' .86 and subsequent opening .of the master control switch :permits .the rotary switch a arm .78 .to .be advanced-to. the next-station .by-v spring action. 7 Figure ,1.0..sho.ws.how .the two. multiple signal unitsllla and 77b.may :be connected. in series with both of their selector .switches'7-2 in their secon'd positions. ,-,In this arrangement, the individual smoke guns are operated in sequence :onqdemand. 'Each time the master control .switch:-10,0 is closed and opened .oneofthepignal guns js operated. .-It:'is--,apparent that :the rotary switch :arm #78 of .thefirstnunit 77a operates the sixssignal rgunsiin the -first-.-unit insuccession and then cooperates with/the second seriesoficontacts 82 toiconne'ct'the master control switchc directly to thesecond unit 77b. The second unit then responds to openingandwclosing of themaster :SWitGh1100 in-the samemanner. "Thus {Figure .ltl'prov ides -twelvessmokexsignals-;on demand in response to closing and-opening act the -Inaster'- control switch .100 twelve times. r

Details :Qf...:c0.nstruction *Thenose'cone 22-is retained in'assembled.positionby a nose fitting (Figure 2) "on the ,endof' alongitudinal "tie rod 123 ,whichtie rodscrewsinto a ,fixed'nut 124 on the forward end of the longitudinal'platform Q70. ln' li'ke --manner {the tail cone 5'24 'is -held in "position 'by a tail fitting (not shown) on the reartend of *atie 'rod 125 (Figure 3;), the other end ofgthetierod being threaded into a 'fixe'd nut 126 of the axialfcylinder 25. It; is apparent that the nose conezl-may be readily removedffor "access to the control compartment :66 and that the {tail cone -24 "maybe 'rea'dily removed 'for 236C688 to ,the' six longitu'dinal compartments '28. As best shown in Figure '4,the"'tail cone '24is provided withian internal'transverse *frame member 130 which holds theforward ends of the :tail pipes 58 in fixed spaced relation'to. mateiwith the cartridge chamber nozzles 35. The particular smoke signal cartridge 3'4 "shown in Figures "3 andfi-is -in theform of acollapsiblecylindrical tubefwhich is filled with the smoke-producing material46 and isthen-sealed=by"a cap 132. Fhe'cartridge may be made of a suitable non-metallic plastic material or may be made ofa soft metal alloy, the material being sufliciently pliable to permit the cartridge to collapse for discharge of its contents in response to exteriorly applied fluid pressure. It is apparent that when compressed air is admitted to a cartridge chamber 32 from the corresponding fluid pressure reservoir 30, the cartridge 34 therein will collapse and the frangible wall 44 at the end of the nozzle 38 will rupture to permit the material to be discharged through the aperture 36 of the cartridge chamber nozzle 35.

In some instances, a collapsible cartridge 34a shown in Figure 14 may be substituted for the collapsible cartridge 34. The cartridge 34:: has a rigid cylindrical wall and is closed at its forward end by a floating wall or piston 134 in cooperation with a suitable O-ring. When the container 34a issubjected to external fluid pressure, the piston 134 is moved longitudinally inward to cause collapse of a frangible wall (not shown) that closes the cartridge nozzle 35a in the manner heretofore described.

Figure 15 shows a third cartridge 35b that may be used interchangeably with the cartridges 35 and 35a. The cartridge 35b is used for the creation of a smoke signal by the discharge of a suitable inert powder, for example, chrome yellow. The cartridge 35b, which may be made entirely of cardboard, has a cylindrical shell closed at its ends by suitable walls in the form of frangible cardboard discs 135 and 136. i

As best shown in Figure 6, the pressure chamber or reservoir 30 of each of the smoke signal guns G may be closed at its opposite ends by heavy transverse walls 137 and 138. To permit replenishment of the charge of compressed air in the reservoir 30, the cylindrical wall of the reservoir is provided with a suitable check valve 142 to function as an intake valve.

Any suitable valve arrangement may be employed for release of the high pressure fluid from the high pressure reservoir 30 into the adjoining cartridge chamber 32 to cause collapse of the smoke producing cartridge therein. Preferably, a pilot-operated valve is provided for this purpose to be actuated by the corresponding solenoid 55.

In the present construction, a main valve 160 and a pilot valve member 161 are mounted in a cylindrical valve casing 162 that is integral with the end wall 138 of the high pressure reservoir 30, the valve casing being surrounded by the pressurized gaseous fluid in the reservoir. The rear end of the valve casing 162 carries a threaded bushing 163 provided with a sealing ring 164, which bushing forms an outlet port 165 in communication with the cartridge chamber 32.

The main valve member 160 has a conical nose which normally seats in the threaded bushing 163 to close the outlet port 165 as shown in Figure 6. The cylindrical valve casing 162 has a peripheral inlet port 166 at the same end as the discharge port 165 to admit high pressure fluid from the chamber 30 and at the other end has an axial. relief port 167 for communication with the atmosphere. When the main valve member 160 is retracted out of its normal seat in the bushing 163 the gaseous fluid confined under pressure in the high pressure reservoir 30 may pass through the peripheral inlet port 166 into the valve casing 162 and out of the valve casing through the outlet port 165 into the cartridge chamber 32 containing the collapsible cartridge 34.

The main valve member 160 is surrounded by a suitable sealing ring 170 held in place by a tapered split retaining ring 171. It is contemplated that a suitable bleeder passage will be provided for equalizing the pressure in the valve casing 162 on the opposite sides of the main valve member'160. For this purpose, the sealing ring 170 may be provided with a small bleeder bore 172 as indicated in Figure 6a. 1 i a The main valve member 160 is of hollow cylindrical construction and is-formed with an inner conical shoulder 173 to cooperatewith a circumferentialseries of four 8 balls 174 that are best shown in Figure 7. Telescoped into the main valve member 160 is a fi xed sleeve 175 in which the pilot valve member 161 is slidingly mounted. The fixed sleeve 175 has small vent bores 176 and is formed with circumferentially spaced. apertures 177 to retain the four balls 174.

The pilot valve'rnember 161 carries a resilient ring 180 to seat against an annular rib 181 at the closed position of the valve mechanism to seal off the previously mentioned relief port 165 that communicates with the atmosphere. As shown in Figure 6, the pilot valve member 161 has an axial projection 182 which extends into the relief port 167 at its closed position. The pilot valve member 161 is preferably of hollow construction and is formed with a circumferential groove 183 for cooperation with the four balls 174. Suitable vent bores 184 (Figure 7) may be provided in the bottom of the circumferential groove 183, as best shown in Figure 7. Preferably a suitable coil spring 185 is in compression between the main valve 160 and the pilot valve member 161 to provide a relatively light force that constantly urges both valve members to their closed positions.

In the normal closed position of the valve mechanism shown in Figure 6, with the main valve member 160 closing the outlet port 165 and the pilot valve member 161 closing the relief port 167, the high pressure fluid confined in the pressure reservoir 30 is in communication with the interior of the valve casing 162 through the peripheral inlet port 166. The fluid pressure in the valve casing 162 on the opposite faces of the main valve member 160 is equalized by virtue of the bleeder bore 172 in the sealing ring 170. Since the nose of the main valve member 160 extending into the outlet port 165 is not exposed to this high pressure the main valve member is subject to a pressure differential that holds it in closed position. In like manner, since a portion of the pilot valve member 161 in the area of the relief port 167 is cut off from the high fluid pressure, the pilot valve member is subject to a similar pressure differential that holds it in closed position. This last pressure differential is of relatively low magnitude, however, because of the smaller areas involved. Thus, only a relativelylight mechanical pressure is required to open the pilot valve member 161 in opposition to its normal pressure differential and in opposition to the relatively light spring 185.

Eln addition to a pressure difierential to urge the main valve member 160 to closed position, the described arrangement further provides a latch to lock it in closed position. The latch mechanism includes the four balls 174, the inner conical shoulder 173 of the main valve member, the fixed sleeve 175 and the circumferential groove 183 around the pilot valve member 161. When the main valve member 160 and the pilot valve member 161 are in their normal closed positions shown in Figure '6, the circumferential groove 183 of the pilot valve is out of register with the four apertures 177 in the fixed sleeve 175 in which the four balls 174 are 'mounted.

When the parts are in these positions, opening movement of the main valve member is prevented in a positive manner by abutment of the inner conical shoulder 173 of the main valve member against the balls 174 and by abutment of the balls 174 against the fixed sleeve 'is unlatched and simultaneously the pressure differential against the main valve member is reversed to move the main valve member to its open position. The reversal of the pressure differential to cause opening movement of the main valve member 160 occurs because the openof the relief port 167 by the pilot valve member 161 releases one ,face of the main valve member from the high prcssure. Unlatching of the main valve member 160 occurs because the opening movement of the pilot valve memberzlflplacesathe circumferential groove 183 of the pilot "valve member .in register with the apertures -177 in the fixed sleeve 175 .to permit the four balls to fbegcannnedjadially inward into the circumferential :groove"183 .bythe inner conical shoulder 173 ofthemain Yalve.\member'160, thus "freeing the main valve member :for. opening movement.

jiJSince one side of the main valve member 160 is .under .Only atmospheric pressure, the main valve member re- .mains open .as "long as any substantial fluid pressure .eXistsin the. region of its nose. When the compressed gaseous fluid is completely discharged, however, the relatively light coil spring 185 returns the main valve member to its closed position and also returns the pilot valve member 161 to its closed position to latch the main valve member.

Any suitable arrangement may be provided to open the pilot valve member 161 in response to energization of the corresponding solenoid 55. In the present construction, the previously mentioned axial tube 54 connects the relief port 167 of the valve casing 162 with an axial port 193 in the end wall 137 of the high pressure reservoir 30. The outer side of the end wall 137 is formed with a threaded cylindrical skirt 194 to receive a cylindrical extension 195 of the solenoid 55 for the purpose of supporting the solenoid. The solenoid 55 which is of a construction to provide communication with the atmosphere is held in place by a suitable bushing 196 that threads onto the cylindrical skirt 194.

The electrically responsive core or armature 57 of the solenoid 55 is normally maintained in retracted position by a suitable spring 200 and is operatively connected with the pilot valve member 161 by a push rod assembly that includes the previously mentioned axial push rod 52. The push rod 52 slidingly extends through a pair of bushings 202 in the cylindrical extension 195 of the solenoid and is connected to a tubular member 203 that slidingly extends through the tube 54.- The tubular member 203, in turn, terminates in a plug or nose member 204 that abuts the axial projection 182 of the pilot valve member 161. It is apparent that normally the spring 200 holds the push rod assembly in retracted position to permit the pilot valve member 161 to remain in closed position, but that energization of the solenoid 55 causes the push rod assembly to shift the pilot valve member 161 from the closed position shown in Figure 6 to its open position, thus causing the main valve member 160 to open in the manner heretofore described.

When the solenoid 55 is energized in the course of flight, the push rod assembly including the push rod 52 is actuated to unseat the pilot valve member 161. This action unlatches the main valve member 160 and simultaneously causes reversal of the pressure differential to cause the opening movement of the main valve member. The high pressure gaseous fluid released from the reservoir 30 into the cartridge chamber 32 by the opening of the main valve member 161 causes sufficient external fluid pressure to be applied to the periphery of the cartridge 34 to cause the cartridge to collapse. The main valve member 160 remains open during this discharge operation but is closed by the spring 185 automatically when the operation terminates.

My description in specific detail of the presently preferred embodiment of the invention will suggest various changes, substitutions and other departures from my disclosure that properly lie within the spirit and scope of the appended claims.

I claim:

1. A multiple-signal unit having in combination: an elongated central housing section for mounting on an rear end of saidcentral housing section, said .tail housing sectionhaving a plurality of discharge passages leading rearwardly from said longitudinal compartments 'respectively, said tail housing sectionbeing removable for access, to said longitudinal compartments; a plurality of .signal guns in saidlongitudinal compartments for discharge of signal material through said discharge lpassages; and a. nose housing section mounted on ,the forward end of said central housing section, said nose housing section being removablev for access to the interior thereof; .and control means enclosed by said nose housing section for operation .of said guns sucessivelyby'remote control.

2. A combination as set forth in claim 1 in which each of said signal guns comprises a fluid pressure reservoir and a cartridge chamber to hold a collapsible cartridge, said cartridge chamber having an open end removably joined with said reservoir for access to the interior of the cartridge chamber to permit replenishment of a cartridge therein.

3. A multiple-signal unit for use on an aircraft to trace the path of flight of the aircraft for detection of the path from a great distance, said unit having in combination: a plurality of longitudinal chambers; a plurality of corresponding discharge passages extending from said chambers to the atmosphere; a plurality of corresponding collapsible containers in said chambers, respectively, each of said containers containing smoke-producing material and having a normally closed pressure-responsive outlet at the inner end of the corresponding discharge passage; a corresponding plurality of valve means and pressurized fluid controlled thereby to create fluid pressure diiferentials between said chamber and the corresponding discharge passages to open said outlets and to collapse the containers for discharging the contents of the containers into said discharge passages; and control means to operate said plurality of valve means in sequence.

4. A combination as set forth in claim 3, in which said control means includes: a plurality of corresponding electrical actuating means to operate said valve means; and a stepping switch to energize said electrical actuating means in sequence.

5. A combination as set forth in claim 4, in which said stepping switch has more operating positions than the number of said valve means whereby the stepping switch may be connected to a second similar multiple-signal unit for operation thereof.

6. A combination as set forth in claim 4, which includes an intervalometer to control the stepping action of said stepping switch.

7. A combination as set forth in claim 6, which includes a normally closed relay responsive to said intervalometer, said stepping switch being responsive to said relay.

8. A combination as set forth in claim 3, in which each of said valve means comprises a normally closed pilot valve and a normally closed main valve responsive thereto; and in which said control means includes a plurality of corresponding solenoids to open said pilot valves.

9. A combination as set forth in claim 3, in which said control means includes: a plurality of corresponding electrical actuating means to open said valve means; a stepping switch to energize said electrical actuating means in sequence; an intervalometer to actuate said stepping switch; a normally open master switch; and a selector switch, said selector switch having one position to connect said master switch directly to the stepping switch and a second position to connect the master switch to said intervalometer for energization thereof.

10. A multiple signal unit for use on an aircraftto trace the path of flight of the aircraft, said unit comprising: a streamlined housing for attachment to the aircraft on the exterior thereof, said unit having a trailing portion; a plurality of longitudinal chambers in said housing; a plurality of corresponding discharge passages extending from said chambers, respectively, to said trailing portion of the housing; a plurality of corresponding collapsible containers in said chambers; respectively, each of said containers containing smoke-producing material and having a normally closed pressure-responsive outlet at the inner end of the corresponding discharge passage;

a plurality of corresponding actuating means to create fluid pressure differentials between said chambers and the corresponding discharge passages to open said outlets and to collapse the containers for discharging said containers into said discharge passages; and control means to operate said plurality of actuating means in sequence.

References Cited in the file of this patent UNITED STATES PATENTS 913,297 Krautschneider Feb. 23, 1909 922,709 Means May 25, 1909 1,503,830 Hineman Aug. 5, 1924 1,823,304 Weller Sept. 15, 1931 2,044,617 Leonard 'Iune 16, 1936 2,308,060 De Roch'efort Lucay Jan. 12, 1943 2,334,552 Hammond Nov. 16, 1943 2,346,325 Oliver Apr. 11, 1944 2,557,120 Knoblock June 19, 1951 Wetzel et a1 June 19, 1951 

